Many rotary fluid pressure devices, such as hydraulic motors or hydraulic pumps, include a gerotor gear set. Typically, the rotary fluid pressure device includes a parking brake, i.e., a lock, to prevent torque transfer, i.e., rotation of the gerotor gear set.
There are many different styles of parking brakes for the gerotor gear set, however, one particular style of parking brake includes a brake pin that is longitudinally moveable along a longitudinal axis into interlocking engagement with a star gear of the gerotor gear set. The brake pin includes a cylindrical portion that slides into an internal opening of the star gear to prevent orbital movement of the star gear about the longitudinal axis. The cylindrical portion of the brake pin engages the internal opening of the star gear in a parallel arrangement along the longitudinal axis. A torque applied to the star gear generates a radial force that is directed inward toward the longitudinal axis. The brake pin resists this radial force and prevents movement of the star gear. However, in the event an overload is applied to the star gear, i.e., a torque greater than an allowable design torque, the interface between the cylindrical portion of the brake pin and the star gear, i.e., the surface of the brake pin and the surface of the star gear, may be damaged. If the overload is great enough, the brake pin and/or the star gear may fracture.